The present invention relates to a tool for machining bore surfaces and particularly to the arrangement of paired cutting edges on a cutting tool body.
Tools of this type, such as boring tools and reamers, are known. Particularly when machining bore surfaces in workpieces made of hardened steel, it has been found that the cutting edges of the tool become chipped and/or chattering occurs during the machining, so that the bore surface does not have the desired size or the desired surface quality.
It is therefore an object of the invention to provide a tool of the type mentioned at the beginning which does not have these disadvantages.
To achieve this object, a tool is proposed which includes a rotatable tool body with a plurality, and preferably at least four, cutting edges, and of the at least four cutting edges, which are arranged in pairs, one pair of cutting edges is offset in the axial direction of the tool body from the other pair.
In an especially advantageous embodiment of the tool, the first pair of cutting edges are arranged symmetrically to one another while the second pair of cutting edges are arranged asymmetrically. That means that the second pair of cutting edges are not arranged exactly diametrically opposite or, as viewed in the axial direction of the tool, are arranged so as to be offset from one another. In an arrangement having an axial offset of one pair of cutting edges or in an arrangement with cutting edges which are not exactly diametrically opposite, it has been found that chipping of the cutting edges and chattering of the tool are avoided, even when machining workpieces made of hardened steel.
In a further preferred embodiment of the tool, at least a third pair of cutting edges is provided. In a tool having at least six cutting edges, the first pair of cutting edges are arranged symmetrically to one another and the second and/or third pair of edges are arranged asymmetrically, as discussed above. This reliably avoids chipping of the cutting edges and chattering of the tool.
Other objects and features of the invention are explained below with reference to the accompanying drawings.